<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>体验css</title>
    <style>
        p {
            color: red;
            font-size: 30px;
            background-color: green;
            width: 400px;
            height: 400px;
        }
    </style>
</head>
<body>
<p>这是这个一个p标签</p>
</body>
</html>